The fuse holder module has an insulator (11) with a socket (12) and a relatively movable fuse holder (13) having at least one eccentric bore for reception of a test plug (26). The test plug bore lies to one side of the centre plane (M) of the fuse holder module with a limb (40) on the opposite side of the centre plane fitting between the two arms (24A,24B) of the auxiliary contact device (24) to provide the contact pressure for the test plug pin (25).
